Conformational effects on high-spin organic molecules

Scott K. Silverman, Dennis A. Dougherty

Research output: Contribution to journalArticle


The ability of m-phenylene to ferromagnetically couple spin-containing substituents that are substantially twisted out of conjugation is investigated. The "bis(TMM)" strategy is employed, in which two triplet TMM biradicals are linked through m-phenylene to produce relatively stable, organic tetraradicals that are characterized by EPR spectroscopy. Under conditions of moderate twisting (4), ferromagnetic coupling is seen, and the tetraradical has a quintet ground state. Severely twisting both TMMs as in 13 disrupts spin communication, and two noninteracting triplets are produced. This is in contrast to other highly twisted m-phenylene derivatives, in which antiferromagnetic coupling has been observed. Surprisingly, severely twisting only one TMM (14) still produces ferromagnetic coupling and a quintet ground state through a spin polarization mechanism analogous to that proposed for 90° twisted ethylene. Several ring-constrained TMMs (17-19) are investigated as models for more nearly planar systems.

Original languageEnglish (US)
Pages (from-to)13273-13283
Number of pages11
JournalJournal of physical chemistry
Issue number50
StatePublished - 1993

ASJC Scopus subject areas

  • Engineering(all)
  • Physical and Theoretical Chemistry

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